Typical variable displacement axial piston devices, e.g. pumps and motors, have a housing, a rotatable drive shaft on the housing, a cylinder barrel on the drive shaft with a plurality of axial pistons in bores in the barrel, and a tilt-yoke which changes the displacement of the axial pistons. The housing is a two-piece assembly including a first half called a mounting flange and a second half called a valve block. The mounting flange carries a first or primary bearing for the drive shaft and the valve block carries a second or secondary bearing for the drive shaft. An annular plate of the tilt-yoke surrounds the drive shaft near the primary bearing. A pair of diametrically opposite trunnions extend from the plate and are supported on the mounting flange by trunnion bearings in trunnion bearing sockets in the mounting flange.
In assembling such common or typical devices, the trunnion bearings are necessarily assembled after the drive shaft and primary bearing are fully assembled on the mounting flange. Then, the trunnion bearings are assembled by sliding each end-wise over a corresponding trunnion and into its sockets. The trunnion bearings are prevented from backing out of the sockets by portions of the valve block which envelop the trunnion bearing sockets. This procedure is not attractive for high volume applications because it is relatively difficult, and therefore time consuming, for an assembler to center the trunnions in the trunnion bearing sockets against various spring forces reacting on the tilt-yoke. The axial piston device according to this invention incorporates novel structure which simplifies the above assembly steps and, further, which facilitates relative alignment between the primary and secondary bearings.